From Longman Dictionary of Contemporary Englishunprovokedun‧pro‧voked /ˌʌnprəˈvəʊkt◂ $ -ˈvoʊkt◂/ adjective WRONG/UNJUSTIFIEDunprovoked anger, attacks etc are directed at someone who has not done anything to deserve them It was a totally unprovoked attack on an innocent man.
Examples from the Corpus
unprovoked• Troops have been accused of unprovoked aggression against innocent civilians.• But if they were used only after proper training and in self-defence, how can that be construed as unprovoked aggression?• It was a totally unprovoked attack and in the end the police were prosecuted for assault.• The unprovoked attack has left the man critically ill in hospital.• A man died in an apparently unprovoked attack in central Oxford last night.• Any Rottweiler that makes an unprovoked attack on a human being should be destroyed.• Yildiz was killed on the streets of Glasgow last weekend in what is thought to have been an unprovoked racist attack. 